linux/kernel/cgroup, branch v5.19

cgroup: Use separate src/dst nodes when preloading css_sets for migration

2022-06-16T19:37:02Z

Each cset (css_set) is pinned by its tasks. When we're moving tasks around across csets for a migration, we need to hold the source and destination csets to ensure that they don't go away while we're moving tasks about. This is done by linking cset->mg_preload_node on either the mgctx->preloaded_src_csets or mgctx->preloaded_dst_csets list. Using the same cset->mg_preload_node for both the src and dst lists was deemed okay as a cset can't be both the source and destination at the same time. Unfortunately, this overloading becomes problematic when multiple tasks are involved in a migration and some of them are identity noop migrations while others are actually moving across cgroups. For example, this can happen with the following sequence on cgroup1: #1> mkdir -p /sys/fs/cgroup/misc/a/b #2> echo $$ > /sys/fs/cgroup/misc/a/cgroup.procs #3> RUN_A_COMMAND_WHICH_CREATES_MULTIPLE_THREADS & #4> PID=$! #5> echo $PID > /sys/fs/cgroup/misc/a/b/tasks #6> echo $PID > /sys/fs/cgroup/misc/a/cgroup.procs the process including the group leader back into a. In this final migration, non-leader threads would be doing identity migration while the group leader is doing an actual one. After #3, let's say the whole process was in cset A, and that after #4, the leader moves to cset B. Then, during #6, the following happens: 1. cgroup_migrate_add_src() is called on B for the leader. 2. cgroup_migrate_add_src() is called on A for the other threads. 3. cgroup_migrate_prepare_dst() is called. It scans the src list. 4. It notices that B wants to migrate to A, so it tries to A to the dst list but realizes that its ->mg_preload_node is already busy. 5. and then it notices A wants to migrate to A as it's an identity migration, it culls it by list_del_init()'ing its ->mg_preload_node and putting references accordingly. 6. The rest of migration takes place with B on the src list but nothing on the dst list. This means that A isn't held while migration is in progress. If all tasks leave A before the migration finishes and the incoming task pins it, the cset will be destroyed leading to use-after-free. This is caused by overloading cset->mg_preload_node for both src and dst preload lists. We wanted to exclude the cset from the src list but ended up inadvertently excluding it from the dst list too. This patch fixes the issue by separating out cset->mg_preload_node into ->mg_src_preload_node and ->mg_dst_preload_node, so that the src and dst preloadings don't interfere with each other. Signed-off-by: Tejun Heo Reported-by: Mukesh Ojha Reported-by: shisiyuan Link: http://lkml.kernel.org/r/1654187688-27411-1-git-send-email-shisiyuan@xiaomi.com Link: https://www.spinics.net/lists/cgroups/msg33313.html Fixes: f817de98513d ("cgroup: prepare migration path for unified hierarchy") Cc: stable@vger.kernel.org # v3.16+

Merge branch 'for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2022-05-25T18:47:25Z

Pull cgroup updates from Tejun Heo: "Nothing too interesting. This adds cpu controller selftests and there are a couple code cleanup patches" * 'for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: remove the superfluous judgment cgroup: Make cgroup_debug static kseltest/cgroup: Make test_stress.sh work if run interactively kselftest/cgroup: fix test_stress.sh to use OUTPUT dir cgroup: Add config file to cgroup selftest suite cgroup: Add test_cpucg_max_nested() testcase cgroup: Add test_cpucg_max() testcase cgroup: Add test_cpucg_nested_weight_underprovisioned() testcase cgroup: Adding test_cpucg_nested_weight_overprovisioned() testcase cgroup: Add test_cpucg_weight_underprovisioned() testcase cgroup: Add test_cpucg_weight_overprovisioned() testcase cgroup: Add test_cpucg_stats() testcase to cgroup cpu selftests cgroup: Add new test_cpu.c test suite in cgroup selftests

cgroup: remove the superfluous judgment

2022-05-20T07:49:45Z

Remove the superfluous judgment since the function is never called for a root cgroup, as suggested by Tejun. Suggested-by: Tejun Heo Signed-off-by: Shida Zhang Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo

cgroup: Make cgroup_debug static

2022-05-18T16:59:20Z

Make cgroup_debug static since it's only used in cgroup.c Signed-off-by: Xiu Jianfeng Signed-off-by: Tejun Heo

cgroup/cpuset: Remove cpus_allowed/mems_allowed setup in cpuset_init_smp()

2022-05-05T18:57:00Z

There are 3 places where the cpu and node masks of the top cpuset can be initialized in the order they are executed: 1) start_kernel -> cpuset_init() 2) start_kernel -> cgroup_init() -> cpuset_bind() 3) kernel_init_freeable() -> do_basic_setup() -> cpuset_init_smp() The first cpuset_init() call just sets all the bits in the masks. The second cpuset_bind() call sets cpus_allowed and mems_allowed to the default v2 values. The third cpuset_init_smp() call sets them back to v1 values. For systems with cgroup v2 setup, cpuset_bind() is called once. As a result, cpu and memory node hot add may fail to update the cpu and node masks of the top cpuset to include the newly added cpu or node in a cgroup v2 environment. For systems with cgroup v1 setup, cpuset_bind() is called again by rebind_subsystem() when the v1 cpuset filesystem is mounted as shown in the dmesg log below with an instrumented kernel. [ 2.609781] cpuset_bind() called - v2 = 1 [ 3.079473] cpuset_init_smp() called [ 7.103710] cpuset_bind() called - v2 = 0 smp_init() is called after the first two init functions. So we don't have a complete list of active cpus and memory nodes until later in cpuset_init_smp() which is the right time to set up effective_cpus and effective_mems. To fix this cgroup v2 mask setup problem, the potentially incorrect cpus_allowed & mems_allowed setting in cpuset_init_smp() are removed. For cgroup v2 systems, the initial cpuset_bind() call will set the masks correctly. For cgroup v1 systems, the second call to cpuset_bind() will do the right setup. cc: stable@vger.kernel.org Signed-off-by: Waiman Long Tested-by: Feng Tang Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo

Merge tag 'driver-core-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2022-03-28T19:41:28Z

Pull driver core updates from Greg KH: "Here is the set of driver core changes for 5.18-rc1. Not much here, primarily it was a bunch of cleanups and small updates: - kobj_type cleanups for default_groups - documentation updates - firmware loader minor changes - component common helper added and take advantage of it in many drivers (the largest part of this pull request). All of these have been in linux-next for a while with no reported problems" * tag 'driver-core-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (54 commits) Documentation: update stable review cycle documentation drivers/base/dd.c : Remove the initial value of the global variable Documentation: update stable tree link Documentation: add link to stable release candidate tree devres: fix typos in comments Documentation: add note block surrounding security patch note samples/kobject: Use sysfs_emit instead of sprintf base: soc: Make soc_device_match() simpler and easier to read driver core: dd: fix return value of __setup handler driver core: Refactor sysfs and drv/bus remove hooks driver core: Refactor multiple copies of device cleanup scripts: get_abi.pl: Fix typo in help message kernfs: fix typos in comments kernfs: remove unneeded #if 0 guard ALSA: hda/realtek: Make use of the helper component_compare_dev_name video: omapfb: dss: Make use of the helper component_compare_dev power: supply: ab8500: Make use of the helper component_compare_dev ASoC: codecs: wcd938x: Make use of the helper component_compare/release_of iommu/mediatek: Make use of the helper component_compare/release_of drm: of: Make use of the helper component_release_of ...

Merge branch 'akpm' (patches from Andrew)

2022-03-24T21:14:07Z

Merge more updates from Andrew Morton: "Various misc subsystems, before getting into the post-linux-next material. 41 patches. Subsystems affected by this patch series: procfs, misc, core-kernel, lib, checkpatch, init, pipe, minix, fat, cgroups, kexec, kdump, taskstats, panic, kcov, resource, and ubsan" * emailed patches from Andrew Morton : (41 commits) Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang" kernel/resource: fix kfree() of bootmem memory again kcov: properly handle subsequent mmap calls kcov: split ioctl handling into locked and unlocked parts panic: move panic_print before kmsg dumpers panic: add option to dump all CPUs backtraces in panic_print docs: sysctl/kernel: add missing bit to panic_print taskstats: remove unneeded dead assignment kasan: no need to unset panic_on_warn in end_report() ubsan: no need to unset panic_on_warn in ubsan_epilogue() panic: unset panic_on_warn inside panic() docs: kdump: add scp example to write out the dump file docs: kdump: update description about sysfs file system support arm64: mm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef x86/setup: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef kexec: make crashk_res, crashk_low_res and crash_notes symbols always visible cgroup: use irqsave in cgroup_rstat_flush_locked(). fat: use pointer to simple type in put_user() minix: fix bug when opening a file with O_DIRECT ...

cgroup: use irqsave in cgroup_rstat_flush_locked().

2022-03-24T02:00:34Z

All callers of cgroup_rstat_flush_locked() acquire cgroup_rstat_lock either with spin_lock_irq() or spin_lock_irqsave(). cgroup_rstat_flush_locked() itself acquires cgroup_rstat_cpu_lock which is a raw_spin_lock. This lock is also acquired in cgroup_rstat_updated() in IRQ context and therefore requires _irqsave() locking suffix in cgroup_rstat_flush_locked(). Since there is no difference between spin_lock_t and raw_spin_lock_t on !RT lockdep does not complain here. On RT lockdep complains because the interrupts were not disabled here and a deadlock is possible. Acquire the raw_spin_lock_t with disabled interrupts. Link: https://lkml.kernel.org/r/20220301122143.1521823-2-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior Acked-by: Tejun Heo Cc: Johannes Weiner Cc: Thomas Gleixner Cc: Zefan Li From: Sebastian Andrzej Siewior Subject: cgroup: add a comment to cgroup_rstat_flush_locked(). Add a comment why spin_lock_irq() -> raw_spin_lock_irqsave() is needed. Link: https://lkml.kernel.org/r/Yh+DOK73hfVV5ThX@linutronix.de Signed-off-by: Sebastian Andrzej Siewior Acked-by: Tejun Heo Cc: Johannes Weiner Cc: Thomas Gleixner Cc: Zefan Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2022-03-23T19:43:35Z

Pull cgroup updates from Tejun Heo: "All trivial cleanups without meaningful behavior changes" * 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: cleanup comments cgroup: Fix cgroup_can_fork() and cgroup_post_fork() kernel-doc comment cgroup: rstat: retrieve current bstat to delta directly cgroup: rstat: use same convention to assign cgroup_base_stat

Merge tag 'v5.17-rc8' into sched/core, to pick up fixes

2022-03-15T09:28:12Z

Signed-off-by: Ingo Molnar